I recently acquired my first Comanche. Have noticed an issue with the steering. When turning either direction, the truck initially turns the other direction briefly and then turns the desired direction. Example: when turning right, the truck turns left then right. When doing so, it feels like the truck almost dives in the opposite direction. I was told the truck possibly needed ball joints replaced ( both upper and lower ) and tie rod replaced. Could this be the source of the problem? Any help would be appreciated. Thanks.
Go through the steering linkage, check for loose parts.
I actually think it's impossible for a worm gear steering box (like your Saginaw) to reverse function like that, it sounds like inertia coupled with very
Tie Rod Ends should be able to compress not more than 1/16"-3/32" (use a large slipjoint plier to test this,) and should rebound fully
. You should be able to grip the linkage with the joint in between your two hands - the joint should pivot, but should not shake or rattle.
(Be careful doing this one!
) With the engine running, transmission in Park, and wheels blocked
, have a helper turn the steering wheel about 20-30* while you're feeling the Pitman arm coming out of the box - it should start moving immediately, and there should be no tactile "clunk" or other vibration, apart from vibes transmitted from the engine. A "small clunk" usually means the box needs to be adjusted (it's doable, check your FSM. If you don't have one, ask and one of us can tell you how to do it,) a "large clunk" usually means the box wants to be rebuilt.
To check the ball joints, you'll need to jack the front end up and get a couple inches or so of daylight under the wheels. Using a long lever (min. four feet, usually,) you'll want to pry under the wheel and feel for looseness or sudden motion - the ball joint is built roughly like the tie rod end, it's just inconvenient to test.
I'm willing to bet you're going to find at least some loose parts - hopefully, just in the steering linkage (it's easiest to replace.)
If a ball joint is going out, replace all four (it can be done in the driveway, you'll just need to source a ball joint press kit. I got an OTC kit from Amazon.com for <$100, don't bother with the kit from Harbour Freight. In the time it took me to bend the HF press, I changed all four ball joints with the OTC.) There is a special sleeve adapter that helps immensely with the D30 front end, but I don't have it and could do the job anyhow.
If the steering box is loose, you can either overhaul it yourself (this would likely be due to wear in the ball bearings on the worm shaft, which usually come with the kit,) or replace it outright (a remanufactured unit will usually serve, I typically use A1Cardone or ACDelco parts for this.) A Saginaw box is easy enough to rebulid and only requires a couple of special tools (mainly a pin-spanner wrench, snapring pliers, and a seal driver kit,) but I wouldn't suggest it for the amateur mechanic - it is fairly easy to screw up.
FSM = Factory Service Manual. With a little luck, you can score on secondhand from eBay for <$40, and it's worth every penny! If you can't find one or need a manual quickly, I would recommend Chilton's over Haynes.
You may use any FSM 1987-1990 for your 1998 MJ, just be advised that some small wiring colours changed ca. AUG88 - however, this isn't a big problem and the vehicles are otherwise identical (I've had no trouble using my 1990 FSM with my 88 XJ, I didn't get an 88 FSM - from AMC - until recently. The 1990 will be printed by ChryCo, but that's not a problem.)
The AMC manuals are big loose-leaf jobs, the ChryCo manuals are bound sets. The 1990 is two books - one for electrical, one for everything else. It will have a maroon cover (ChryCo changed cover colours to help tell different years apart - my 89 is bright red, my 90 is maroon/dark red, my 91 is black, my 94 is yellow, my 96 is purple, ...)